This invention relates to actuation mechanisms for tools in a downhole environment, such as reamers. Various efforts to provide reliable mechanical actuation of downhole tools are disclosed in the prior art.
U.S. Pat. No. 4,893,678 to Stokley et al. discloses a downhole tool suitable for multiple setting and unsetting operations in a well bore during a single trip. The downhole tool is suspended in the wellbore from a tubing string, and is activated by dropping a metal ball which plugs the passageway through the tubing string, such that tubing pressure may thereafter be increased to activate the downhole tool. A sleeve is axially movable within a control sub from a ball stop position to a ball release position, and has a cylindrical-shaped interior surface with a diameter only slightly greater than the ball. Collet fingers carried on the sleeve are radially movable from an inward position to an outward position to stop or release the ball as a function of the axial position of the sleeve. Fluid flow through the tubing string is thus effectively blocked when the sleeve is in the ball stop position because of the close tolerance between the sleeve and the ball, while the ball is freely released from the sleeve and through the downhole tool when the sleeve is moved to the ball release position.
U.S. Pat. No. 4,889,199 to Lee discloses a downhole drilling device utilizing a spring-loaded sleeve within the casing for controlling circulation of fluid material. A plastic, i.e., deformable ball is used to block a flow opening in the sleeve for positioning the sleeve and aligning flow ports. Subsequently, the ball is deformed and the drilling operation continues. In one form, an expandable packer may be operated to close off the annulus about the casing.
U.S. Pat. No. 7,416,029 to Telfer discloses a downhole tool which can perform a task in a well bore, such as circulating fluid radially from the tool. The function is selectively performed by virtue of a sleeve moving within a central bore of the tool. Movement of the sleeve is effected by dropping a ball through a ball seat on the sleeve. Movement of the sleeve is controlled by an index sleeve such that the tool can be cycled back to the first operating position by dropping identical balls through the sleeve. Embodiments are described wherein the balls are deformable, the seat is deformable and the seat provides a helical channel through which the ball passes.
U.S. Pat. No. 3,703,104 to Tamplen discloses a positioning apparatus for effecting movement of a first body with respect to a second body in response to movement of a third body characterized by a slot traversal member engaging a set of driving slots and a set of driven slots that are formed respectively in the first and second bodies. One of the sets of driven and driving slots comprises a closed pattern of slots; and the other comprises a single slot having at least two portions that have the same design and are movable so as to be coextensive with the slots of the closed pattern of slots. Also disclosed are tubular and planar constructions employing the driving and driven slots.